1. Field of the Invention
This invention relates to a scroll compressor, and more particularly, to a configuration of a fixed scroll and an orbiting scroll of the scroll compressor capable of obtaining a sufficient compression ratio.
2. Background of the Invention
A scroll compressor is a compressor which includes a fixed scroll having a fixed wrap and an orbiting scroll having an orbiting wrap engaged with the fixed wrap. In this configuration of the scroll compressor, as the orbiting scroll orbits on the fixed scroll, the volumes of compression chambers, which are formed between the fixed wrap and the orbiting wrap, consecutively change, thereby sucking and compressing a refrigerant.
The scroll compressor allows suction, compression and discharge to be consecutively performed, so it is very favorable, as compared to other types of compressors, in the aspect of vibration and noise generated during operation.
The behavior of the scroll compressor may be dependent on the shapes of the fixed wrap and the orbiting wrap. The fixed wrap and the orbiting wrap may have a random shape, but typically they have a shape of an involute curve, which is easy to manufacture. The involute curve refers to a curve corresponding to a track drawn by an end of a thread when unwinding the thread wound around a basic circle with a predetermined radius. When such an involute curve is used, the wrap has a uniform thickness, and a rate of volume change of the compression chamber in response to a rotated angle of the orbiting scroll is constantly maintained. Hence, the number of turns of the wrap should increase to obtain a sufficient compression ratio, which may, however, cause the compressor to be increased in size corresponding to the increased number of turns of the wrap.
The orbiting scroll typically includes a disk, and the orbiting wrap is located at one side of the disk. A boss is formed at a rear surface of the disk opposite to the side at which the orbiting wrap is formed. The boss is connected to a rotation shaft, which allows the orbiting scroll to perform an orbiting motion. Such an arrangement with the orbiting wrap on one side of the disk and the boss on the other side of the disk allows the orbiting wrap to be formed on almost an entire surface of the disk, thereby reducing a diameter of the disk for obtaining a particular compression ratio. However, a point of application of a driving force at the boss which is opposed to a force of a refrigerant upon compression between the fixed wrap and the orbiting wrap is perpendicularly spaced apart from the wraps. Because the boss is not in the same plane on the same surface as the orbiting wrap, the orbiting scroll is inclined during operation, thereby generating more vibration and noise.